Ultrasonic flowmeter having pressure balancing system for high pressure operation

ABSTRACT

A system is provided with an ultrasonic flow meter. The ultrasonic flow meter includes a first ultrasonic transducer disposed about a fluid flow path, and a pressure balancing system configured to pressure balance the first ultrasonic transducer relative to a fluid flow along the fluid flow path.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Non-Provisional patentapplication Ser. No. 13/975,235, entitled “Ultrasonic Flowmeter HavingPressure Balancing System for High Pressure Operation”, filed on Aug.23, 2013, which is herein incorporated by reference in its entirety, andwhich claims priority to and benefit of U.S. Non-Provisional patentapplication Ser. No. 13/106,782, entitled “Ultrasonic Flowmeter HavingPressure Balancing System for High Pressure Operation”, filed on May 12,2011, which is herein incorporated by reference in its entirety, andwhich claims priority to and benefit of U.S. Provisional PatentApplication No. 61/448,629, entitled “Ultrasonic Flowmeter HavingPressure Balancing System for High Pressure Operation”, filed Mar. 2,2011, which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to chemical-injection management systems.More particularly, the present invention relates to high-pressurechemical-injection management systems that can measure low flow rates.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Wells are often used to access resources below the surface of the earth.For instance, oil, natural gas, and water are often extracted via awell. Some wells are used to inject materials below the surface of theearth, e.g., to sequester carbon dioxide, to store natural gas for lateruse, or to inject steam or other substances near an oil well to enhancerecovery. Due to the value of these subsurface resources, wells areoften drilled at great expense, and great care is typically taken toextend their useful life.

Chemical-injection management systems are often used to maintain a welland/or enhance throughput of a well. For example, chemical-injectionmanagement systems are used to inject corrosion-inhibiting materials,foam-inhibiting materials, wax-inhibiting materials, and/or antifreezeto extend the life of a well or increase the rate at which resources areextracted from a well. Typically, these materials are injected into thewell in a controlled manner over a period of time by thechemical-injection management system using a flow meter. Unfortunately,existing flow meters are unable to provide accurate measurements at highpressures and low flow rates.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription of certain exemplary embodiments is read with reference tothe accompanying drawings in which like characters represent like partsthroughout the drawings, wherein:

FIG. 1 is a block diagram of an embodiment of an exemplary resourceextraction system;

FIG. 2 is a block diagram of an embodiment of an exemplary resourceextraction system with a chemical injection management system;

FIG. 3 is a partial perspective view of an embodiment of thechemical-injection management system of FIG. 2;

FIG. 4 is a block diagram of an embodiment of the flow regulator in FIG.3 with a low flow ultrasonic flow meter;

FIG. 5 is a cross-sectional perspective view of an embodiment of a lowflow ultrasonic flow meter;

FIG. 6 is a cross-sectional perspective view of an embodiment of a lowflow ultrasonic flow meter;

FIG. 7 is a cross-sectional perspective view of an embodiment of a lowflow ultrasonic flow meter with a pressure adjusting mechanism;

FIG. 8 is a cross-sectional perspective view of an embodiment of a lowflow ultrasonic flow meter with a pressure adjusting mechanism;

FIG. 9 is a cross-sectional perspective view of an embodiment of a lowflow ultrasonic flow meter with acoustic signal damping particles;

FIG. 10 is a cross-sectional view of an embodiment of a low flowultrasonic flow meter with a pressure adjusting mechanism; and

FIG. 11 is a cross-sectional view of an embodiment of a low flowultrasonic flow meter with a pressure adjusting mechanism.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. These described embodiments are only exemplary of thepresent invention. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Moreover, the use of “top,” “bottom,” “above,” “below,” and variationsof these terms is made for convenience, but does not require anyparticular orientation of the components.

Certain exemplary embodiments of the present invention a low flowultrasonic flow meter capable of measuring low flow rates, whileoperating under high-pressure conditions. In certain embodiments, thelow flow ultrasonic flow meter may be used with, coupled to, orgenerally associated with underwater equipment, such as subseaequipment, in a variety of applications. For example, embodiments of thelow flow ultrasonic flow meter may be used with, coupled to, orgenerally associated with mineral extraction equipment, flow controlequipment, pipelines, and the like. In one embodiment, as discussed indetail below, the low flow ultrasonic flow meter may be used with,coupled to, or generally associated a chemical-injection managementsystem. However, the foregoing examples are not intended to be limiting.

In certain embodiments, the low flow ultrasonic flow meter may bedesigned to operate with pressures ranging between approximately 0 to50,000 psi, while the flow rates may range between approximately 0.01 to1000 liters/hour. For example, the flow meter may be configured tomeasure low flow rates less than approximately 0.01, 0.02, 0.03, 0.04,0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10,15, 20, or 25 liters/hour, while operating under pressures up to orgreater than 5,000 psi, 10,000 psi, 15,000 psi, 20,000 psi, 25,000 psi,30,000 psi, 40,000 psi, or 50,000 psi. However, the disclosedembodiments are not limited to any specific operating ranges, and thedisclosed ranges are intended to be non-limiting examples.

Ultrasonic transducers in combination with acoustic damping allow theflow meter to measure the low chemical flow rates in thechemical-injection management system. In certain embodiments, theultrasonic transducers rapidly switch back and forth between acting asan actuator to produce ultrasonic waves, and acting as a sensor todetect ultrasonic waves. For example, an upstream transducer sendssignals downstream through the chemical fluid to a downstreamtransducer, while the downstream transducer sends signals upstreamthrough the chemical fluid to the upstream transducer. The time requiredby the signals to reach the opposing transducer determines the flow rateof the chemical fluid through the chemical injection management system.

As discussed in detail below, the accuracy of the transducers depends onthe acoustic isolation of the transducers from acoustic noise, which caninterfere with the communication through the chemical fluid between thetransducers. For example, the transducers may be covered in polyetherether ketone (PEEK) in combination with a PEEK acoustic isolator toblock acoustic noise and communication between the transducers outsideof the chemical fluid. In some embodiments, the conduit carrying thechemical fluid may be covered in PEEK in combination with PEEK coveredtransducers to block acoustic noise and communication outside of thechemical fluid. In some embodiments, a chamber may surround the conduit,house the transducers, and provide acoustic damping. For example, thechamber may be filled with an acoustic damping material, such as afluid, particles, structures, or a combination thereof.

The flow meter may also include a pressure balancing system that permitsoperation of the flow meter at high pressures. For example, the pressurebalancing system may include the chamber around the conduit, wherein thechamber includes the transducers and is pressure balanced with theconduit. In certain embodiments, the conduit and the chamber may be influid communication with one another. The equalization of the pressurein the conduit and chamber prevents damage to the ultrasonictransducers. In other embodiments, a pressure adjusting/balancingmechanism may be disposed at an interface between the chamber and theconduit, thereby enabling pressure balancing between the conduit and thechamber. For example, the pressure adjusting/balancing mechanism mayinclude a bellows, a balloon, a diaphragm, a piston-cylinder assembly,gel slugs in biros, or any combination thereof. For example, thebellows, balloon, or diaphragm may be made of an expandable/compressiblematerial, such as an elastomer. As the chemical fluid changes pressure,the pressure adjusting/balancing mechanism moves (e.g., expands andcontracts) maintaining a pressure equilibrium between the conduit andthe chamber. However, in certain embodiments, the pressureadjusting/balancing mechanism may include a variety of movable elements,which are configured to balance fluid pressure internal and external tothe conduit by moving the element in response to a pressure differentialbetween the chamber and the conduit. In this manner, the pressureadjusting/balancing mechanism reduces stress on the conduit, therebyprotecting the ultrasonic transducers coupled to the conduit over a widerange of pressures. Although the disclosed embodiments are presented incontext of an ultrasonic flow meter, the disclosed embodiments may beused with any type of flow meters using various sensors or transducerscoupled to the conduit.

FIG. 1 depicts an exemplary sub-sea resource extraction system 10. Inparticular, the sub-sea resource extraction system 10 may be used toextract oil, natural gas, and other related resources from a well 12,located on a sub-sea floor 14, to an extraction point 16 at a surfacelocation 18. The extraction point 16 may be an on-shore processingfacility, an off-shore rig, or any other extraction point. The sub-searesource extraction system 10 may also be used to inject fluids, such aschemicals, steam, and so forth, into the well 12. These injected fluidsmay aid the extraction of resources from the well 12.

As sub-sea resource extraction systems 10 become more complex, reachgreater depths, extend to greater offshore distances, and operate athigher pressures, the auxiliary equipment which supply working fluids tothese sub-sea resource extraction systems 10 increase in complexity aswell. The working fluids may be supplied to the sub-sea equipment usingflexible jumper or umbilical lines 20. The systems may be comprised ofreinforced polymer and small diameter steel supply lines, which areinterstitially spaced into a larger reinforced polymer liner. As theworking pressure of the sub-sea equipment increases, the supplypressures and injection pressures also increase.

FIG. 2 depicts an exemplary resource extraction system 10, which mayinclude a well 12, colloquially referred to as a “Christmas tree” 26(hereinafter, a “tree”), a chemical-injection management system(C.I.M.S.) 28, and a valve receptacle 30. The illustrated resourceextraction system 10 may be configured to extract hydrocarbons (e.g.,oil and/or natural gas). When assembled, the tree 26 may couple to thewell 12 and include a variety of valves, fittings, and controls foroperating the well 12. The chemical-injection management system 28 maybe coupled to the tree 26 via the valve receptacle 30. The tree 26 maypermit fluid communication between the chemical-injection managementsystem 28 and the well 12. As explained below, the chemical-injectionmanagement system 28 may be configured to regulate the flow of achemical through the tree 26 and into the well 12 through use of a flowregulator 32.

FIG. 3 is a perspective view of the chemical-injection management system28, mated with the valve receptacle 30. As illustrated, thechemical-injection management system 28 may include the flow regulator32, a housing 36, a tree interface 38, key 52, and an ROV (remotelyoperated vehicle) interface 40. The housing 36 may include an outer-endplate 42, a sidewall 44, a handle 46, and an inner-end plate. Thesidewall 44 and end plates 42 may be made from a generally rigid,corrosion-resistant material and may generally define a rightcylindrical volume with a circular base. The handle 46 may be affixed(for example, welded) to the sidewall 44 and may have a U-shape. Thetree interface 38 allows connection of the chemical-injection managementsystem 28 to the tree 26 via complementary components on the valvereceptacle 30.

The illustrated ROV interface 40 may include apertures 66, a flared grip68, slots 70 and 72, and a torque-tool interface 74. In someembodiments, the ROV interface 40 may be an API 17D class 4 ROVinterface. The ROV interface 40 may be attached to the outer-end plate42. The torque-tool interface 74, which may be configured to couple to atorque tool on an ROV, may be disposed within the flared grip 68 andgenerally symmetrically between the slots 70 and 72. The torque-toolinterface 74 may be coupled to an internal drive mechanism to carry outthe commands of the ROV.

Valve receptacle 30 may include a fluid inlet 82, a fluid outlet 84, anelectrical connection 86, a mounting flange 88, a keyway 90, supportflanges 92, an outer flange 94, a valve aperture 96, a valve tray 98,and tray supports 100. The fluid inlet 82 may be a fluid conduit, tube,or conduit that fluidly communicates with a fluid source, such as asupply of a liquid to be injected, and the fluid outlet 84 may be afluid conduit, tube, or conduit that is in fluid communication with thewell 12. The electrical connection 86 may couple to a power source, auser input device, a display, and/or a system controller. The mountingflange 88 may be configured to couple the valve receptacle 30 to thetree 26. The keyway 90 and the valve tray 98 may be configured to atleast roughly align the chemical-injection management system 28 to thevalve receptacle 30 during an installation of the chemical-injectionmanagement system 28. Specifically, the valve tray 98 may be configuredto support the chemical-injection management system 28 as it slides intothe valve aperture 96, and the key 52 may be configured to slide intothe keyway 90 to rotationally position the chemical-injection managementsystem 28.

FIG. 4 is a block diagram of an embodiment of the flow regulator 32 inFIG. 3 with a low flow ultrasonic flow meter 120. As discussed in detailbelow, the flow meter 120 may include an acoustic isolation system and apressure balancing system configured to improve performance andoperability of the flow meter 120 over a greater range of pressures andflow rates. In addition to the flow meter 120, the flow regulatorincludes a controller 122, valve drive 124, and valve 126. As discussedbelow, the flow regulator 32 may be configured to regulate or control aflow parameter, such as a volumetric flow rate, a mass flow rate, avolume, and/or a mass of fluid flowing to or from the well 12. The flowmeter 120 may include a fluid inlet 128, a fluid outlet 130, and ameasurement signal path 132. The measurement signal path 132 providessignal data to the controller 122 for processing.

The controller 122 may include a processor 134 and memory 136. Thecontroller 122 may be configured to determine a volumetric flow rate, amass flow rate, a volume, or a mass based on a signal from the flowmeter 120. The controller 122 may also be configured to regulate orcontrol one or more of these parameters based on the signal from theflow meter 120 by signaling the valve drive 124 to adjust the valve 126.To this end, the controller 122 may include software and/or circuitryconfigured to execute a control routine. In some embodiments, thecontrol routine and/or data based on a signal from the flow meter 120may be stored in memory 136 or another computer-readable medium.

The illustrated valve drive 124 may include a motor 138, a gearbox 140,and a control signal path 142 to the controller 122. In operation, thecontroller 122 may exercise feedback control over fluid flow. Thecontroller 122 may transmit a control signal 142 to the valve drive 124.The content of the control signal 142 may be determined by, or based on,a comparison between a flow parameter (e.g., a volumetric flow rate, amass flow rate, a volume, or a mass) measured by the flow meter 120 anda desired value of the flow parameter. For instance, if the controller122 determines that the flow rate through the flow regulator 32 is lessthan a desired flow rate, the controller 122 may signal 142 the valvedrive 124 to open valve 126 some distance. In response, the motor 138may drive the gearbox 140, and the gearbox 140 may convert rotationalmovement from the motor 138 into linear translation of the valve 126, orrotation of the valve 126. As a result, in some embodiments, the flowrate through the valve 126 may increase as the valve opens.Alternatively, if the controller 122 determines that the flow rate (orother flow parameter) through the flow regulator 32 is greater than adesired flow rate (or other flow parameter), the controller 122 maysignal 142 the valve drive 124 to close the valve 126 some distance,thereby potentially decreasing the flow rate. In other words, thecontroller 122 may signal the valve drive 124 to open or close the valve126 some distance based on a flow parameter sensed by the flow meter120.

FIG. 5 is a cross-sectional perspective view of an embodiment of a lowflow ultrasonic flow meter 120. The flow meter 120 defines a housing160, ultrasonic meter system 162, acoustic isolator system 164, and apressure balance system 166. As discussed in detail below, the housing160 defines a chamber 213 surrounding a conduit 218, wherein the chamber213 includes the ultrasonic meter system 162, the acoustic isolatorsystem 164, and the pressure balancing system 166. In the illustratedembodiment, the housing 160 includes a lid 170 that connects to a bodyportion 172. The lid 170 includes a midsection 174 with a front face 176and a rear face 178. A circular protrusion 179 extends from the frontface 176 to an end face 180. The lid's 170 rear face 178 similarlyincludes a circular protrusion 182, which has a side face 184 an endface 186.

The lid 170 may include multiple apertures. For example, the lid 170includes multiple bolt apertures 188, gasket apertures 190, and a fluidpassage 192. The bolt apertures 188 receive bolts 194, while the gasketapertures receive gaskets 196 (e.g., annular gaskets or seals). In thepresent embodiments, the gasket apertures 190 and gaskets 196 arelocated on the rear face 178 of the lid 170, and the side face 184 ofthe circular protrusion 182. These gaskets 196 form a fluid tight sealbetween the lid 170 and the body 172. The fluid passage 192 extendsbetween the face 180 of the circular protrusion 179 and the face 186 ofthe circular protrusion 182. This allows fluid to flow through the lid170, e.g., fluid flow measured by the flow meter 120.

The body 172 defines a front face 198, a rear face 200, a flow meteraperture 202, and a circular protrusion 204 extending from the frontface 198. The flow meter aperture 202 defines a diameter 206, an innersurface 208, and a wall 210. The rear face 200 further defines boltapertures 212. The lid 170 attaches to the body 172 by inserting thecircular protrusion 182 into the flow meter aperture 202. As mentionedabove, the flow meter aperture 202 defines a diameter 206, which isequal to or greater than the circular protrusion 182. The protrusion 182slides into the aperture 202 until the rear face 178 of the lid 170contacts the rear surface 200 of the body 172. The lid 170 may then becircumferentially rotated about the body 172 until the bolt apertures188 align with the bolt apertures 212. The bolts 194 extend into theapertures 188, 212 and threadingly secure the lid 170 to the body 172.As explained above, the gaskets 196 are compressed between the two rearfaces 178 and 200, and between the inner surface 208 and the surface 184to create a fluid tight seal between the lid 170 and the body 172. Thejoining of the lid 170 to the body 172 creates a flow meterchamber/static fluid chamber 213 that houses the ultrasonic meter system162, acoustic isolation system 164, and pressure balance system 166.

The ultrasonic flow meter 120 includes a through passage 161 defined bypassage 192 in the lid 170, a passage 214 in the body 172, and a conduit218 extending through the chamber 213 between passages 192 and 214. Theultrasonic meter system 162 measures parameters, e.g., a flow rate,along the passage 161. The passage 214 extends between the face 216 ofthe protrusion 204 and wall 210. Accordingly, fluid may enter the flowmeter 120 through the passage 214, flow through the body 172 into thechamber 213, flow through conduit 218 to the passage 192, and then exitthrough the passage 192 of the lid 170.

As the fluid passes through the flow meter 120, the ultrasonic metersystem 162 measures its flow rate. The ultrasonic meter system 162includes conduit 218, ultrasonic transducers 220 and 222, and controller122. As illustrated, the transducers 220 and 222 are annular in shape.In other embodiments, the transducers 220 and 222 may vary in shape,e.g., flat, square, oval, etc. The transducers 220 and 222 measure thefluid entering the flow meter 120 and traveling through the conduit 218.As illustrated, the ultrasonic transducers 220 and 222 are mountedaround the conduit 218 at an axial offset distance 224 relative to oneanother. The ultrasonic transducers 220 and 222 measure flow speeds byrapidly sending and receiving ultrasonic waves that travel through thefluid in the conduit 218. For example, the upstream transducer 222 maysend ultrasonic waves through the fluid traveling in conduit 218 to thedownstream transducer 220. The controller 122 collects the transmissiontimes by the upstream transducer 222 and the reception times by thedownstream transducer 220 through wires 226. The controller 122 thencalculates ultrasonic wave speed in the fluid using the distance 224 andthe time between transmission and reception. The ultrasonic wave speedis then compared to the known speed of ultrasonic waves in the samefluid over the same distance, while the fluid is motionless. The wavespeed differences determine how fast the fluid is moving in the conduit218, i.e., the faster the fluid speed in conduit 218 the less time ittakes the ultrasonic waves to travel from the upstream transducer 222 tothe downstream transducer 220. Similarly, the faster the fluid speed thelonger it will take the ultrasonic waves to travel from the transmittingdownstream transducer 220 to the receiving upstream transducer 222. Oncefluid speed is known, the controller 122 may calculate flow rate bymultiplying the fluid speed by πd²/4 (i.e., conduit area), wherein “d”equals the diameter 228 of conduit 218. With this information, the flowregulator 32 may increase, decrease, or maintain the chemical fluid flowrate, e.g., through operation of the valve 126 (as illustrated in FIG.4). In some embodiments, both transducers 220 and 222 may transmit andreceive ultrasonic waves, which the controller 122 may use to determinefluid speed in the pipe. The comparison of the two speeds mayadvantageously provide increased accuracy of the fluid speedcalculation.

As mentioned above, the flow meter 120 may include an acoustic isolationsystem 164. The acoustic isolation system 164 is configured to blockacoustic noise and communications outside of the fluid in the conduit218, thereby ensuring that the transducers 220 and 222 communicate onlythrough the fluid in the conduit 218 without interference. This acousticisolation enables more accurate sensing of the fluid flow rate insidethe conduit 218. For example, the acoustic isolation system 164 mayenable accurate measurement of flow rates as low as 0.03 liters/hour(e.g., less than 0.05, 1, 2, 3, 4, 5, 10, 15, or 20 liters/hour), and ashigh as 120 liters/hour. In the present embodiment, the acousticisolation system 164 may use polyether ether ketone (PEEK) to blockand/or absorb acoustic noise, interference, and ultrasonic waves createdby the transducers 220 and 222 outside of the fluid in the conduit 218.Other embodiments may use a different material to block and/or absorbthe ultrasonic wave energy, acoustic noise, or interference. Forexample, the acoustic isolation system 164 may encapsulate thetransducers 220 and 222 with isolative structures 230 (e.g., acousticdamping structures). As illustrated, the isolative structures 230 arering shaped, but may form other shapes, e.g., square, irregular, oval,rectangular etc. Furthermore, these isolative structures 230 may be madeof an acoustic damping material, such as PEEK, an elastomer, a polymer,a foam, or a combination thereof. These PEEK rings 230 absorb ultrasonicwaves created by their respective transducer 220 or 222, and wavescreated by the opposing transducer 220 or 222 outside of the fluid inthe conduit 218. For example, the PEEK rings 230 may absorb ultrasonicwave energy transmitted through fluid in chamber 213, and through thewall 219 of conduit 218. For example, the PEEK ring 230 coveringtransducer 220 absorbs waves produced by transducer 220 and bytransducer 222 outside of the conduit 218, while enabling the transducer220 to transmit and receive ultrasonic wave energy at an interface 221with the conduit 218. Similarly, the ring 230 covering transducer 222absorbs waves produced by transducer 222 and by transducer 220 outsideof the conduit 218, while enabling the transducer to transmit andreceive ultrasonic wave energy at an interface 223 with the conduit 218.

In addition to PEEK rings 230, the acoustic isolator system 164 mayinclude a third acoustic isolative structure 232 (e.g., acoustic dampingstructure) for absorbing acoustic noise, interference, and ultrasonicwaves created by the transducers 220 and 222 outside of the conduit 218.For example, the third acoustic isolative structure 232 may absorbacoustic noise, interference, and ultrasonic waves traveling through thewall 219 of the conduit 218. The ultrasonic waves traveling through theconduit wall 219 may travel at a different speed than the ultrasonicwaves traveling through the fluid, and thus the acoustic isolativestructure 232 absorbs this energy to improve measurement accuracy.Accordingly, the acoustic isolative structure 232 is mounted axiallybetween the transducers 220 and 222. As illustrated, the acousticisolative structure 232 encircles and extends along the conduit 218,while also including a conduit interruption or annular blockade 233axially between portions of the conduit 218. In the illustratedembodiment, the system 164 includes a single third ring 232, while otherembodiments may include other shapes of the isolative structure 232,e.g., square, oval, rectangular, irregular, etc. Furthermore, the system164 may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more isolativestructures 232 between the transducers 220 and 222. Furthermore, each ofthese structures 232 may vary in thickness and/or type of acousticmaterial.

Finally, the flow meter 120 may include a pressure balance system 166that protects the transducers 220 and 222 in high pressuresenvironments. In certain embodiments, the pressures may range betweenapproximately 0 to 50,000 psi, while the flow rates may range betweenapproximately 0.01 to 1000 liters/hour. For example, the flow meter maybe configured to measure low flow rates less than approximately 0.01,0.02, 0.03, 0.04, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1,2, 3, 4, 5, 10, 15, 20, or 25 liters/hour, while operating underpressures up to or greater than 5,000 psi, 10,000 psi, 15,000 psi,20,000 psi, 25,000 psi, 30,000 psi, 40,000 psi, or 50,000 psi. Thepressure balance system 166 includes the chamber 213, conduit 218, andelectrical connector plug 234. As illustrated, the conduit 218 includesthe wall 219 that surrounds a passage 235 that extends through thechamber 213 from a first end 236, to a second end 238. The first end 236is coupled to the passage 192 in the lid 170. The second end 239 extendsinto a counterbore 240 of the wall 210 of the body portion 172. Thefirst end 236 is sealed relative to the passage 192, while the secondend 238 is not sealed to the passage 214. Instead, an axial gap 242exists between the second end 238 and the passage 214. In addition, thecounterbore 240 defines a diameter 244 greater than the conduit diameter228, thereby creating an annular gap 246. The combination of the gaps242 and 246 creates a fluid connection 247 between the chamber 213, theconduit 218, and the passage 214. This fluid connection 247 between thefluid in the conduit 218 and the chamber 213 allows for an equalizationof pressure.

Without pressure equalization, the conduit may compress or expand to thepoint that transducers 220 and 222 break or lose their connection withthe conduit 218. For example, if the pressure in the conduit 218 exceedsthe pressure inside the chamber 213 the conduit wall 219 may expanddiametrically. Similarly, if the pressure in the chamber 213 exceeds thepressure in the conduit 218, then the wall 219 may compressdiametrically. The compression and expansion of the conduit wall 219 maycause the transducers 220, 222 to break or separate from the conduit218, preventing proper transmission and reception of ultrasonic wavestraveling through the fluid in the conduit 218. Thus, the fluidconnection 247 enables the fluid to pressure balance between the chamber213 and the conduit 218 to increase an operational range of the flowmeter 120 to higher pressures, e.g., greater than 10,000 psi, 15,000psi, 20,000 psi, 25,000 psi, 30,000 psi, 40,000 psi, or 50,000 psi.

The electrical connection plug 234 maintains communication between theultrasonic meter system 162 and the controller 122. More specifically,the electrical connection plug 234 permits electrical communicationbetween the transducers 220 and 222, while maintaining pressure and afluid tight seal. For example, the electrical connection plug 234 mayfit within and adhere to a passage 248 within the body 172. For example,the plug 234 may be threaded, welded, press fitted in the passage 248.The plug 234 may retain fluid within the chamber 213 without leakage atpressures of greater than 10,000 psi, 15,000 psi, 20,000 psi, 25,000psi, 30,000 psi, 40,000 psi, or 50,000 psi.

The electrical connection plug 234 includes a body portion 250 (e.g., anelectrically insulative body portion) and electrically conductiveportions 252 (e.g., wires) disposed in apertures 254 and 256. Theseelectrically conductive portions 252 couple to wires 226 from thetransducers 220 and 222 and wires 258 from the controller 122. The wires226 and 258 and the electrically conductive portions 252 enableelectrical signals to pass from the transducers 220 and 222 within theflow meter 120 to the exterior controller 122, while the body portion250 maintains a seal of the chamber 213. Accordingly, the three systems:ultrasonic meter system 162, acoustic isolator system 164, and pressurebalance system 166 permit accurate low flow rate measurement in ahigh-pressure environment.

FIG. 6 is a cross-sectional perspective view of an embodiment of a lowflow ultrasonic flow meter 120. Similar to the flow meter 120 of FIG. 5,the flow meter 120 in FIG. 6 includes a housing 270, ultrasonic metersystem 272, acoustic isolator system 274, and a pressure balance system276. In the illustrated embodiment, the housing 270 includes a lid 278that connects to a body portion 280. The lid 278 connects to the body280 via bolts 282. As illustrated, the lid 278 and the body portion 282include a passage that allows fluid to pass through the flow meter 120.Specifically, the lid 278 includes an exit passage 284, while the body280 includes an entrance passage 286 or vice versa. The passages 284 and286 connect to a chamber 288 within the housing 270.

The ultrasonic meter system 272 is located within the chamber 288, andas discussed above measures the flow rate of fluid through the flowmeter 120. The ultrasonic flow meter system 272 includes an upstreamtransducer 290 and a downstream transducer 292 (or vice versa) thatattach to a conduit wall 295 of a conduit 294. The ultrasonictransducers 290 and 292 may send or receive ultrasonic waves to theopposite transducer through the fluid traveling in the conduit 294. Thecontroller 122 receives the transmission and reception times of theultrasonic waves from the transducers 290 and 292 through electricalconnections 296 and then determines their speed using an offset distance298 between the transducers 290 and 292. As discussed above, the fastera fluid is traveling in the conduit 294, the faster a wave will travelfrom the upstream transducer 290 to the downstream transducer 292.Likewise, a fast moving fluid will slow a wave traveling against thecurrent from the downstream transducer 292 to the upstream transducer290. With this information, the controller 122 is able to determine theflow rate of the fluid by comparing the speed of the wave in the flowmeter to a known speed of the wave in a motionless fluid.

As mentioned above, the flow meter 120 includes an acoustic isolationsystem 274. The acoustic isolation system 274 is configured to blockacoustic noise and communications outside of the fluid in the conduit294, thereby ensuring that the transducers 290 and 292 only communicatewith each other through the fluid in the conduit 294. This acousticisolation enables more accurate sensing of the fluid flow rate insidethe conduit 294. For example, the acoustic isolation system 274 mayadvantageously enable accurate measurement of flow rates as low as 0.03liters/hour (e.g., less than 0.05, 1, 2, 3, 4, 5, 10, 15, or 20liters/hour), and as high as 120 liters/hour. In the present embodiment,the acoustic isolation system 274 covers the conduit 294; and thetransducers 290 and 292 with an acoustic damping material, e.g., a PEEKshell 297. The PEEK shell 297 may block and/or dampen acoustic noise,interference or ultrasonic waves in the chamber 288, therebysubstantially reducing interference with the transducers 290 and 292. Inother words, the PEEK shell 297 may block or dampen all acoustic wavesother then the desired transmission of ultrasonic waves through thefluid in the conduit 294 between the transducers 290 and 292.Furthermore, the PEEK of the shell 297 may also serve as a protectivebarrier or chemical resistant coating, which may protect the transducers290 and 292 from corrosion by chemicals in the chamber 288. Thus, thePEEK shell 297 may simultaneously dampen acoustics and chemicallyprotect the transducers 290 and 292. The PEEK shell 297 may also dampenor absorb ultrasonic energy that may be traveling in the conduit wall295 (i.e., waves travel at a different speed in the conduit wall 295relative to waves traveling through the fluid in the conduit 294). Thus,the PEEK shell 297 surrounding the conduit 294 and transducers 290 and292 enables the acoustic isolation system 274 to protect the conduit294, while absorbing waves not traveling through the fluid in conduit294.

The flow meter 120 also includes the pressure balance system 276. Thepressure balance system 276 includes the chamber 288, conduit 294, andelectrical connector plug 300. The pressure balance system 276 allowsthe ultrasonic meter system 274 to operate in pressure ranges betweenapproximately 0 to 50,000 psi, while the flow rates may range betweenapproximately 0.01 to 1000 liters/hour. For example, the flow meter maybe configured to measure low flow rates less than approximately 0.01,0.02, 0.03, 0.04, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1,2, 3, 4, 5, 10, 15, 20, or 25 liters/hour, while operating underpressures up to or greater than 5,000 psi, 10,000 psi, 15,000 psi,20,000 psi, 25,000 psi, 30,000 psi, 40,000 psi, or 50,000 psi.

As illustrated, the conduit 294 extends through the chamber 288 from afirst end 302, which connects to the passage 284, to a second end 304.The second end 304 sits in a counterbore 306 formed in a wall 308 of thechamber 288. Unlike the first end 302, which connects to passage 284,the second end 304 does not connect to the passage 286. Instead, a gap310 exists between the second end 304 and the passage 286. In addition,the counterbore 306 defines a diameter 312 that is greater than adiameter 313 of the PEEK covered conduit 294. This distance creates asecond gap 314. The combination of the first and second gaps 310, 314creates a fluid connection 315 between the chamber 288, the conduit 294,and the passage 286. This fluid connection 315 allows for anequalization of pressure between the fluid in the conduit 294 and thechamber 288. The pressure equalization limits or prevents compressionand expansion of the conduit 294 that may break the transducers 290 and292 or cause them to lose their connection to the conduit 294. Finally,as discussed above, the pressure balance system 276 includes theelectrical connection plug 300. The electrical connection plug 300permits electrical communication between the transducers 290 and 292,while maintaining a pressure and fluid tight seal. As illustrated, theelectrical connection plug 300 may fit within and adhere to a passage316 within the body 280. In particular, the plug 300 permits electricalcommunication between the transducers 290 and 292 with the controller122, while withstanding pressures up to or greater than approximately5,000 psi, 10,000 psi, 15,000 psi, 20,000 psi, 25,000 psi, 30,000 psi,40,000 psi, or 50,000 psi.

FIG. 7 is a cross-sectional side view of an embodiment of a low flowultrasonic flow meter 120 with pressure equalizing mechanism 340. Forexample, the pressure equalizing mechanism 340 may include a bellows,such as an expandable and contractible bellows. By further example, thepressure equalizing mechanism 340 may include a bellows, a balloon, adiaphragm, a piston-cylinder assembly, gel slugs in biros, or anycombination thereof. For example, the bellows, balloon, or diaphragm maybe made of an expandable/compressible material, such as an elastomer.Similar to the flow meter 120 of FIG. 5, the flow meter 120 in FIG. 7includes a housing 342, ultrasonic meter system 344, acoustic isolatorsystem 346, and a pressure balance system 348. In the illustratedembodiment, the housing 342 includes a lid 350 that connects to a bodyportion 352. Together, the lid 350 and body portion 352 define a chamber353. As illustrated, the lid 350 and the body portion 352 each define apassage that allows fluid to pass through the flow meter 120.Specifically, the lid 350 defines an exit passage 354, while the body352 defines an entrance passage 356 or vice versa. The passages 354 and356 connect to a conduit 358 at respective first and second ends 360 and362 of a conduit wall 359.

As illustrated, the ultrasonic meter system 344 includes transducers 364and 366, electrical lines 368, and controller 122. The ultrasonictransducers 364 and 366 may send or receive ultrasonic waves to theopposite transducer through the fluid traveling in the conduit 358. Thecontroller 122 receives the transmission and reception times of theultrasonic waves from the transducers 364 and 366 through electricallines 368, which it then uses to calculate the fluid speed in theconduit 358. As discussed above, the faster a fluid is traveling in theconduit 358 the faster a wave will travel from the upstream transducer366 to the downstream transducer 364. Likewise, a fast moving fluid willslow a wave traveling against the current from the downstream transducer364 to the upstream transducer 366. With this information, thecontroller 122 is able to determine the flow rate of the fluid bycomparing the speed of the wave in the flow meter to a known speed ofthe wave in a motionless fluid.

As illustrated, the flow meter 120 includes the acoustic isolationsystem 346. The acoustic isolation system 346 uses PEEK rings 370 toprevent the transducers 364 and 366 from communicating with each otherexcept through the fluid traveling in conduit 358. For example, theacoustic isolation system 346 may advantageously allow for accuratemeasurement of flow rates as low as 0.03 liters/hour (e.g., 0.05, 1, 2,3, 4, 5, 10, 15, or 20 liters/hour), and as high as 120 liters/hour. Inthe present embodiment, the acoustic isolation system 346 includes athird PEEK ring 372 for absorbing ultrasonic waves created by thetransducer 364 and 366. The ring 372 is disposed axially between thetransducers 364 and 366, such that it absorbs ultrasonic wave energytraveling through the conduit wall 359. While the present embodimentsillustrate a single third ring 372, in other embodiments there may bemore rings in-between the transducers 364 and 366. For example, theremay be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 rings in-between the transducers364 and 366. Furthermore, each of these rings may vary in thickness andor type of absorbing material with respect to the other rings. In thepresent embodiment, the pressure equalizing mechanism 340 (e.g.,bellows) may permit a second fluid to occupy the chamber 353 surroundingthe conduit 358 such that the second fluid is isolated from the firstfluid flowing through the conduit 350. The second fluid may bespecifically selected based on acoustic damping properties, e.g., thesecond fluid may be a protective liquid that will not corrode thehousing 342, the PEEK rings 370 and 372, or otherwise negatively affectthe system. For example, the second fluid may include oil. In someembodiments, the second fluid may advantageously include fine particlesthat promote acoustic damping (e.g., sand, beads, foam, etc.).

The flow meter 120 may also include the pressure balance system 348. Thepressure balance system 348 includes the chamber 353, conduit 358,pressure equalizing mechanism 340 (e.g., bellows), and electricalconnector plug 374. The pressure balance system 348 allows theultrasonic meter system 344 to operate in pressure ranges betweenapproximately 0 to 50,000 psi, while the flow rates may range betweenapproximately 0.01 to 1000 liters/hour. For example, the flow meter maybe configured to measure low flow rates less than approximately 0.01,0.02, 0.03, 0.04, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1,2, 3, 4, 5, 10, 15, 20, or 25 liters/hour, while operating underpressures up to or greater than 5,000 psi, 10,000 psi, 15,000 psi,20,000 psi, 25,000 psi, 30,000 psi, 40,000 psi, or 50,000 psi.

As illustrated, the pressure equalizing mechanism 340 (e.g., bellows)replaces or extends around a section 376 of the conduit 358. Thepressure equalizing mechanism 340 (e.g., bellows) may be made out ofmetal, rubber, neoprene, vinyl, silicone, or other material that expandsand contracts in response to changes in pressure. The expansion andcontraction of the pressure equalizing mechanism 340 (e.g., bellows)advantageously permits pressure equalization, while allowing a secondfluid to occupy the chamber 353. For example, the conduit 358 mayinclude perforations or passages 378 on the section 376 to enable fluidtraveling through the conduit 358 to enter the pressure equalizingmechanism 340 (e.g., bellows). Thus, during an increase in pressure inthe conduit 358, the fluid passes through the passages 378 and into thepressure equalizing mechanism 340 (e.g., bellows), causing expansion ofthe pressure equalizing mechanism 340 (e.g., bellows) to pressureequalize with the chamber 353. Likewise, during a decrease in pressurein the conduit 358, the pressure equalizing mechanism 340 (e.g.,bellows) contracts and forces fluid through the passages 378 in thesection 376 and into the conduit 358, thereby enabling pressureequalization as the pressure equalizing mechanism 340 (e.g., bellows)expands and contracts in response to pressure changes, accordingly, theconduit 358 does not experience significant stresses (i.e., the conduit358 does not expand or compress). As explained above, the expansion andcontraction of the conduit 358 may break or loosen the connection of thetransducers 366 and 368, which may prevent or limit accuratemeasurement. Finally, the pressure balance system 348 includes anelectrical connection plug 374. The electrical connection plug 374permits electrical communication between the transducers 364 and 366 andthe controller 122, while maintaining a fluid tight seal undersignificant pressure.

FIG. 8 is a cross-sectional side view of an embodiment of a low flowultrasonic flow meter 120 with a PEEK pressure equalizing mechanism 390for pressure equalization, acoustic damping, and corrosion protection.In certain embodiments, the pressure equalizing mechanism 390 mayinclude a bellows, a balloon, a diaphragm, a piston-cylinder assembly,gel slugs in biros, or any combination thereof. Similar to the flowmeter 120 of FIG. 7, the flow meter 120 in FIG. 8 includes a housing392, ultrasonic meter system 394, acoustic isolator system 396, and apressure balance system 398. In the illustrated embodiment, the housing392 includes a lid 400 that connects to a body portion 402. Together,the lid 400 and body portion 402 define a chamber 404. As illustrated,the lid 400 and the body portion 402 each define a passage that allowsfluid to pass through the flow meter 120. Specifically, the lid 400defines an exit passage 406, while the body 402 defines an entrancepassage 408 or vice versa. The passages 406 and 408 connect with aconduit 410 at respective first and second ends 412 and 414 of a conduitwall 411.

As illustrated, the ultrasonic meter system 394 includes transducers 416and 418, electrical lines 420, and controller 122. The ultrasonictransducers 416 and 418 may send or receive ultrasonic waves to theopposite transducer through the fluid traveling in the conduit 410. Asexplained above, the controller 122 uses the transmission and receptionof the ultrasonic waves between the transducers 416 and 418 to calculatethe flow rate of the fluid in the conduit 410.

Furthermore, the flow meter 120 includes the acoustic isolation system396. The acoustic isolation system 396 uses PEEK rings 422 and a PEEKpressure equalizing mechanism 390 (e.g., bellows) to prevent thetransducers 416 and 418 from communicating with each other exceptthrough the fluid traveling in conduit 410. For example, PEEK rings 422encapsulate the transducers 416 and 422 preventing them fromtransmitting ultrasonic waves through the fluid in the chamber 404. Asillustrated, the PEEK pressure equalizing mechanism 390 (e.g., bellows)may also be included axially between the transducers 416 and 422. ThePEEK pressure equalizing mechanism 390 (e.g., bellows) effectivelyabsorbs ultrasonic energy traveling through the conduit wall 411, thus,only ultrasonic waves traveling in the fluid reach the transducers 416and 422. In some embodiments, the PEEK pressure equalizing mechanism 390(e.g., bellows) may permit a second fluid to occupy the chamber 404surrounding the conduit 410. The second fluid may be an oil, or otherfluid that will not corrode the housing 392, the PEEK rings/bellows422/390, or otherwise negatively affect the system. The second fluid mayadvantageously include fine particles that promote acoustic damping(e.g., sand, beads, foam, etc.).

The flow meter 120 may also include the pressure balance system 398. Thepressure balance system 398 includes the pressure equalizing mechanism390 (e.g., bellows), chamber 404, conduit 410, and electrical connectorplug 424. The pressure balance system 398 allows the ultrasonic metersystem 394 to operate in pressure ranges between approximately 0 to50,000 psi, while the flow rates may range between approximately 0.01 to1000 liters/hour. For example, the flow meter may be configured tomeasure low flow rates less than approximately 0.01, 0.02, 0.03, 0.04,0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10,15, 20, or 25 liters/hour, while operating under pressures up to orgreater than 5,000 psi, 10,000 psi, 15,000 psi, 20,000 psi, 25,000 psi,30,000 psi, 40,000 psi, or 50,000 psi.

As illustrated, the conduit 410 may include the PEEK pressure equalizingmechanism 390 (e.g., bellows) replacing or extending around a section426 of the conduit 410. The pressure equalizing mechanism 390 (e.g.,bellows) advantageously permits pressure equalization by expanding whenthe fluid traveling in conduit 410 increases in pressure, andcontracting when the pressure drops. For example, the conduit 410 mayhave one or more passages 428 formed in the section 426 within thepressure equalizing mechanism 390 (e.g., bellows). As the chemical fluidflowing through the conduit 410 experiences an increase in pressure, thefluid flows out of the section 426 through passages 428 and into thebellows section 390, causing it to expand. Similarly, if the chemicalfluid reduces in pressure in the conduit 410, then the fluid leaves thepressure equalizing mechanism 390 (e.g., bellows) and enters the conduit410, thereby enabling pressure equalization. The expansion andcontraction of the pressure equalizing mechanism 390 (e.g., bellows)reduces or eliminates pressure differentials that could cause expansionor contraction of the conduit 410. As explained above, the expansion andcontraction of the conduit 410 may break or loosen the connection of thetransducers 416 and 418, which may prevent or limit accuratemeasurement. Finally, as discussed above, the pressure balance system398 includes the electrical connection plug 424. The electricalconnection plug 424 permits electrical communication between thetransducers 416 and 418, and the controller 122, while maintaining afluid tight seal under pressure.

FIG. 9 is a cross-sectional side view of an embodiment of a low flowultrasonic flow meter 120 with particles 448 configured to dampenacoustical noise. Similar to the flow meter 120 of FIG. 5, the flowmeter 120 in FIG. 9 includes a housing 450, ultrasonic meter system 452,acoustic isolation system 454, and a pressure balance system 456. In theillustrated embodiment, the housing 450 defines passages that allowfluid to pass through the flow meter 120, specifically, an exit passage458 and an entrance passage 460 or vice versa. In addition, the housing450 defines a chamber 462 that houses the ultrasonic meter system 452,the acoustic isolation system 454, and the pressure balance system 456.

As illustrated, the ultrasonic meter system 452 includes transducers 464and 466, electrical lines 468, and controller 122. The ultrasonictransducers 464 and 466 may send or receive ultrasonic waves to theopposite transducer through the fluid traveling in the conduit 470. Asexplained above, the controller 122 uses the transmission and receptionof the ultrasonic waves between the transducers 464 and 466 to calculatethe flow rate of the fluid in the conduit 470.

As illustrated, the flow meter 120 includes the acoustic isolationsystem 454. The acoustic isolation system 454 uses PEEK rings 472 toprevent the transducers 464 and 466 from communicating with each otherexcept through the fluid traveling in conduit 470. For example, theacoustic isolation system 454 may allow for accurate measurement of flowrates as low as 0.03 liters/hour (e.g., less than 0.05, 1, 2, 3, 4, 5,10, 15, or 20 liters/hour), and as high as 120 liters/hour. In thepresent embodiment, the acoustic isolation system 454 includes a thirdPEEK ring 474 for absorbing ultrasonic wave energy traveling throughconduit wall 475. While the present embodiments illustrate a singlethird ring 474, in other embodiments there may be more rings of similaror varying sizes in-between the transducers 464 and 466. In addition tothe rings 472 and 474, the acoustic isolation system 454 may includeparticles 448 within the chamber 462. The particles 448 may absorbacoustic noise traveling through the fluid in the chamber 462, whilesimultaneously limiting fluid motion in chamber 462, i.e., limitingfluid motion prevents the creation of acoustical noise. The particlesmay also deflect the acoustical noise, i.e., preventing the waves fromtraveling in a straight path, which may help block acoustics. Theparticles 448 may be made out of PEEK, rubber, neoprene, vinyl, siliconeor other substances that may absorb acoustic noise and are capable ofenduring a chemical environment. Furthermore, the particles 448 may takeon a variety of shapes and sizes, e.g., circular, oval, irregular, etc.

The flow meter 120 may also include the pressure balance system 456. Thepressure balance system 456 includes the chamber 462, conduit 470, andelectrical connector plug 478. The pressure balance system 456 allowsthe ultrasonic meter system 452 to operate in pressures betweenapproximately 0 to 50,000 psi, while the flow rates may range betweenapproximately 0.01 to 1000 liters/hour. For example, the flow meter maybe configured to measure low flow rates less than approximately 0.01,0.02, 0.03, 0.04, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1,2, 3, 4, 5, 10, 15, 20, or 25 liters/hour, while operating underpressures up to or greater than 5,000 psi, 10,000 psi, 15,000 psi,20,000 psi, 25,000 psi, 30,000 psi, 40,000 psi, or 50,000 psi.

As illustrated, the conduit 470 extends through the chamber 462 from afirst end 480, which connects to the passage 458, to a second end 482.The second end 482 sits in a counterbore 486 formed in a wall 488 of thechamber 462. Unlike the first end 480, which connects to passage 458,the second end 482 does not connect to the passage 460 or the sidesurface 490 of the counterbore 486. This produces a gap 492 that allowsa fluid connection 494 between the chamber 462, the conduit 470, and thepassage 460. The fluid connection 494 allows for an equalization ofpressure between the fluid in the conduit 470 and the chamber 462. Thepressure equalization limits or prevents compression and expansion ofthe conduit 470 that may break the transducers 464 and 466 or cause themto lose their connection to the conduit 470. Finally, as discussedabove, the pressure balance system 456 includes the electricalconnection plug 478. The electrical connection plug 478 permitselectrical communication between the transducers 464 and 466 and thecontroller 122.

FIG. 10 is a cross-sectional side view of an embodiment of a low flowultrasonic flow meter 120 with a pressure equalizing mechanism 500. Forexample, the pressure equalizing mechanism 500 may include apiston-cylinder assembly 501 having a piston 502 disposed in a cylinder504. In the illustrated embodiment, the piston 502 includes one or moreseals, such as first and second annular seals or rings 506 and 508,which are disposed in annular seal grooves 510 and 512, respectively.The piston 502 may be made of any suitable material, such as metal,plastic, ceramic, cermet, or any combination thereof. For example, thepiston 502 may be made of a stainless steel. Furthermore, the seals 506and 508 may be made from any suitable material, such as metal, plastic,fabric, or any combination thereof. In some embodiments, the piston 502may exclude the seals 506 and 508 and associated seal grooves 510 and512. Some embodiments also may employ a coating 514 disposed along anexterior surface 516 of the piston 502 and/or an interior surface 518 ofthe cylinder 504. The coating 514 may include a corrosion resistantcoating, a wear resistant coating, a low friction coating, or anycombination thereof. For example, the coating 514 may include a lowfriction coating, such as polytetrafluoroethylene (PTFE) or Teflon. Byfurther example, the coating 514 may include a wear resistant coating,such as tungsten carbide.

In the illustrated embodiment, the piston 502 moves along an axis 520 ofthe cylinder 504 between opposite first and second ends 522 and 524 ofthe cylinder 504 in response to pressure changes between opposite firstand second fluid chambers 526 and 528, respectively. In particular, thefirst fluid chamber 526 is defined between the first end 522 of thecylinder 504 and a first end 530 of the piston 502, while the secondfluid chamber 528 is defined between the second end 524 of the cylinder504 and a second end 532 of the piston 502. As the pressure changes inthe first and second fluid chambers 526 and 528, the piston 502 movesalong the axis 520 of the cylinder 504 to pressure balance the first andsecond fluid chambers 526 and 528. In the illustrated embodiment, thepiston 502 has a cylindrical shaped body 534, which may be solid orhollow. Similarly, the cylinder 504 has a cylindrical shaped geometry536 to accommodate the cylindrical shaped body 534 of the piston 502.However, other embodiments of the piston 502 and the cylinder 504 mayhave other geometrical shapes, such as oval, rectangular, polygonal, andso forth. Furthermore, some embodiments of the pressure equalizingmechanism 500 may include a plurality of pistons 502 disposed in thecylinder 504, or a plurality of piston-cylinder assemblies 501 eachhaving at least one piston 502 disposed in a cylinder 504. In otherembodiments, the piston 504 may be replaced with a bellows, diaphragm,or other pressure balancing mechanism in the cylinder 504. As discussedbelow, the piston-cylinder assembly 501 is configured to providepressure balancing to increase the operational pressure range of the lowflow ultrasonic flow meter 120.

In addition, the low flow ultrasonic flow meter 120 of FIG. 10 includesa housing 540, ultrasonic meter system 542, acoustic isolator system544, and a pressure balance system 546. In the illustrated embodiment,the housing 540 includes a lid 548 that connects to a body portion 550.Together, the lid 548 and body portion 550 define a chamber 552. Asillustrated, the lid 548 and the body portion 550 each define a passagethat allows fluid to pass through the flow meter 120. Specifically, thelid 548 defines a first passage 554, while the body 550 defines a secondpassage 556. In one embodiment, the first passage 554 is an entrancepassage while the second passage 556 is an exit passage. In anotherembodiment, the first passage 554 is an exit passage while the secondpassage 556 is an entrance passage. The passages 554 and 556 connect toa conduit 558 at respective first and second ends 560 and 562 of aconduit wall 564.

As illustrated, the ultrasonic meter system 542 includes transducers 566and 568, electrical lines 570, and controller 122. The ultrasonictransducers 566 and 568 may send or receive ultrasonic waves to theopposite transducer through the fluid traveling in the conduit 558. Thecontroller 122 receives the transmission and reception times of theultrasonic waves from the transducers 566 and 568 through electricallines 570, which it then uses to calculate the fluid speed in theconduit 558. As discussed above, the faster a fluid is traveling in theconduit 558 the faster a wave will travel from the upstream transducer568 to the downstream transducer 566, or vice versa. Likewise, a fastmoving fluid will slow a wave traveling against the current from thedownstream transducer 566 to the upstream transducer 568, or vice versa.With this information, the controller 122 is able to determine the flowrate of the fluid by comparing the speed of the wave in the flow meterto a known speed of the wave in a motionless fluid.

As further illustrated in FIG. 10, the flow meter 120 includes theacoustic isolation system 544. The acoustic isolation system 544 usesacoustic isolation rings 572 to prevent the transducers 566 and 568 fromcommunicating with each other except through the fluid traveling inconduit 558. For example, the acoustic isolation rings 572 may be madeof an acoustic isolation material, such as PEEK, and thus the rings 572may be described as PEEK rings 572. The acoustic isolation system 544may advantageously allow for accurate measurement of flow rates as lowas 0.03 liters/hour (e.g., 0.05, 1, 2, 3, 4, 5, 10, 15, or 20liters/hour), and as high as 120 liters/hour. In the present embodiment,the acoustic isolation system 544 includes a third acoustic isolationring 574 (e.g., a PEEK ring) for absorbing ultrasonic waves created bythe transducer 566 and 568. The ring 574 is disposed axially between thetransducers 566 and 568, such that it absorbs ultrasonic wave energytraveling through the conduit wall 564. While the present embodimentsillustrate a single third ring 574, in other embodiments there may bemore rings in-between the transducers 566 and 568. For example, theremay be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 rings in-between the transducers566 and 568. Furthermore, each of these rings may vary in thickness andor type of absorbing material with respect to the other rings. In thepresent embodiment, the pressure equalizing mechanism 500 (e.g.,piston-cylinder assembly 501) may permit a second fluid to occupy thechamber 552 surrounding the conduit 558 such that the second fluid isisolated from the first fluid flowing through the conduit 548. Thesecond fluid may be specifically selected based on acoustic dampingproperties, e.g., the second fluid may be a protective liquid that willnot corrode the housing 540, the PEEK rings 572 and 574, or otherwisenegatively affect the system. For example, the second fluid may includeoil. In some embodiments, the second fluid may advantageously includefine particles that promote acoustic damping (e.g., sand, beads, foam,etc.).

The flow meter 120 may also include the pressure balance system 546. Thepressure balance system 546 includes the chamber 552, conduit 558,pressure equalizing mechanism 500 (e.g., piston-cylinder assembly 501),and electrical connector plug 576. The pressure balance system 546allows the ultrasonic meter system 542 to operate in pressure rangesbetween approximately 0 to 50,000 psi, while the flow rates may rangebetween approximately 0.01 to 1000 liters/hour. For example, the flowmeter may be configured to measure low flow rates less thanapproximately 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10, 15, 20, or 25 liters/hour, whileoperating under pressures up to or greater than 5,000 psi, 10,000 psi,15,000 psi, 20,000 psi, 25,000 psi, 30,000 psi, 40,000 psi, or 50,000psi.

In the illustrated embodiment, the pressure equalizing mechanism 500(e.g., piston-cylinder assembly 501) is radially offset away from thefluid chamber 552, but connects both to the fluid chamber 552 and thefluid flow path through the flow meter 120. For example, the illustratedpressure equalizing mechanism 500 includes first and second conduits orpassages 578 and 580, which couple to the first and second fluidchambers 526 and 528 of the cylinder 504. Thus, the passage 578communicates fluid between the fluid chambers 526 and 552, such that thechambers 526 and 552 are at substantially the same pressure as oneanother. Likewise, the passage 580 communicates fluid between the fluidchamber 528 and the passage 556, such that the chamber 528 and passage556 are at substantially the same pressure as one another. Asappreciated, the piston 502 includes the seals 506 and 508 to isolatethe fluid in the passage 556 from the fluid in the chamber 552.Accordingly, the fluids may be the same or different from one another.The piston 502 also moves along the axis 520 of the cylinder 504 topressure balance the fluid in the passage 556 with the fluid in thechamber 552.

Thus, during an increase in pressure in the passage 556, the fluidpasses through the passage 580 and into the fluid chamber 528, therebybiasing the piston 502 to move from the chamber 528 toward the chamber526 until a pressure balance is reached between the chambers 526 and 528(and thus between the passage 556 and chamber 552). Likewise, during adecrease in pressure in the passage 556, the fluid passes through thepassage 578 and into the fluid chamber 526, thereby biasing the piston502 to move from the chamber 526 toward the chamber 528 until a pressurebalance is reached between the chambers 526 and 528 (and thus betweenthe passage 556 and chamber 552). Finally, the pressure balance system546 includes an electrical connection plug 576. The electricalconnection plug 576 permits electrical communication between thetransducers 566 and 568 and the controller 122, while maintaining afluid tight seal under significant pressure.

FIG. 11 is a cross-sectional side view of an embodiment of a low flowultrasonic flow meter 120 with a pressure equalizing mechanism 600. Forexample, the pressure equalizing mechanism 600 may include apiston-cylinder assembly 601 having a piston 602 disposed in a cylinder604. In the illustrated embodiment, the piston 602 includes one or moreseals, such as first and second annular seals or rings 606 and 608,which are disposed in annular seal grooves 610 and 612, respectively.The piston 602 may be made of any suitable material, such as metal,plastic, ceramic, cermet, or any combination thereof. For example, thepiston 602 may be made of a stainless steel. Furthermore, the seals 606and 608 may be made from any suitable material, such as metal, plastic,fabric, or any combination thereof. In some embodiments, the piston 602may exclude the seals 606 and 608 and associated seal grooves 610 and612. Some embodiments also may employ a coating 614 disposed along anexterior surface 616 of the piston 602 and/or an interior surface 618 ofthe cylinder 604. The coating 614 may include a corrosion resistantcoating, a wear resistant coating, a low friction coating, or anycombination thereof. For example, the coating 614 may include a lowfriction coating, such as polytetrafluoroethylene (PTFE) or Teflon. Byfurther example, the coating 614 may include a wear resistant coating,such as tungsten carbide.

In the illustrated embodiment, the piston 602 moves along an axis 620 ofthe cylinder 604 between opposite first and second ends 622 and 624 ofthe cylinder 604 in response to pressure changes between opposite firstand second fluid chambers 626 and 628, respectively. In particular, thefirst fluid chamber 626 is defined between the first end 622 of thecylinder 604 and a first end 630 of the piston 602, while the secondfluid chamber 628 is defined between the second end 624 of the cylinder604 and a second end 632 of the piston 602. As the pressure changes inthe first and second fluid chambers 626 and 628, the piston 602 movesalong the axis 620 of the cylinder 604 to pressure balance the first andsecond fluid chambers 626 and 628. In the illustrated embodiment, thepiston 602 has a cylindrical shaped body 634, which may be solid orhollow. Similarly, the cylinder 604 has a cylindrical shaped geometry636 to accommodate the cylindrical shaped body 634 of the piston 602.However, other embodiments of the piston 602 and the cylinder 604 mayhave other geometrical shapes, such as oval, rectangular, polygonal, andso forth. Furthermore, some embodiments of the pressure equalizingmechanism 600 may include a plurality of pistons 602 disposed in thecylinder 604, or a plurality of piston-cylinder assemblies 601 eachhaving at least one piston 602 disposed in a cylinder 604. In otherembodiments, the piston 604 may be replaced with a bellows, diaphragm,or other pressure balancing mechanism in the cylinder 604. As discussedbelow, the piston-cylinder assembly 601 is configured to providepressure balancing to increase the operational pressure range of the lowflow ultrasonic flow meter 120.

In addition, the low flow ultrasonic flow meter 120 of FIG. 11 includesa housing 640, ultrasonic meter system 642, acoustic isolator system644, and a pressure balance system 646. In the illustrated embodiment,the housing 640 includes a lid 648 that connects to a body portion 650.Together, the lid 648 and body portion 650 define a chamber 652. Asillustrated, the lid 648 and the body portion 650 each define a passagethat allows fluid to pass through the flow meter 120. Specifically, thelid 648 defines a first passage 654, while the body 650 defines a secondpassage 656. In one embodiment, the first passage 654 is an entrancepassage while the second passage 656 is an exit passage. In anotherembodiment, the first passage 654 is an exit passage while the secondpassage 656 is an entrance passage. The passages 654 and 656 connect toa conduit 658.

As illustrated, the ultrasonic meter system 642 includes transducers 666and 668 and associated electrical lines and controller, as discussed indetail above with reference to FIG. 10. The ultrasonic transducers 666and 668 may send or receive ultrasonic waves to the opposite transducerthrough the fluid traveling in the conduit 658. The controller 122receives the transmission and reception times of the ultrasonic wavesfrom the transducers 666 and 668 through electrical lines, which it thenuses to calculate the fluid speed in the conduit 658. As discussedabove, the faster a fluid is traveling in the conduit 658 the faster awave will travel from the upstream transducer 668 to the downstreamtransducer 666, or vice versa. Likewise, a fast moving fluid will slow awave traveling against the current from the downstream transducer 666 tothe upstream transducer 668, or vice versa. With this information, thecontroller 122 is able to determine the flow rate of the fluid bycomparing the speed of the wave in the flow meter to a known speed ofthe wave in a motionless fluid.

As further illustrated in FIG. 11, the flow meter 120 includes theacoustic isolation system 644. The acoustic isolation system 644 usesacoustic isolation rings 672 to prevent the transducers 666 and 668 fromcommunicating with each other except through the fluid traveling inconduit 658. For example, the acoustic isolation rings 672 may be madeof an acoustic isolation material, such as PEEK, and thus the rings 672may be described as PEEK rings 672. The acoustic isolation system 644may advantageously allow for accurate measurement of flow rates as lowas 0.03 liters/hour (e.g., 0.05, 1, 2, 3, 4, 6, 10, 15, or 20liters/hour), and as high as 120 liters/hour. In the present embodiment,the acoustic isolation system 644 includes a third acoustic isolationring 674 (e.g., a PEEK ring) for absorbing ultrasonic waves created bythe transducer 666 and 668. The ring 674 is disposed axially between thetransducers 666 and 668, such that it absorbs ultrasonic wave energytraveling through the conduit wall 664. While the present embodimentsillustrate a single third ring 674, in other embodiments there may bemore rings in-between the transducers 666 and 668. For example, theremay be 1, 2, 3, 4, 6, 6, 7, 8, 9, or 10 rings in-between the transducers666 and 668. Furthermore, each of these rings may vary in thickness andor type of absorbing material with respect to the other rings. In thepresent embodiment, the pressure equalizing mechanism 600 (e.g.,piston-cylinder assembly 601) may permit a second fluid to occupy thechamber 652 surrounding the conduit 658 such that the second fluid isisolated from the first fluid flowing through the conduit 648. Thesecond fluid may be specifically selected based on acoustic dampingproperties, e.g., the second fluid may be a protective liquid that willnot corrode the housing 640, the PEEK rings 672 and 674, or otherwisenegatively affect the system. For example, the second fluid may includeoil. In some embodiments, the second fluid may advantageously includefine particles that promote acoustic damping (e.g., sand, beads, foam,etc.).

The flow meter 120 may also include the pressure balance system 646. Thepressure balance system 646 includes the chamber 652, conduit 658, andpressure equalizing mechanism 600 (e.g., piston-cylinder assembly 601).The pressure balance system 646 allows the ultrasonic meter system 642to operate in pressure ranges between approximately 0 to 50,000 psi,while the flow rates may range between approximately 0.01 to 1000liters/hour. For example, the flow meter may be configured to measurelow flow rates less than approximately 0.01, 0.02, 0.03, 0.04, 0.05,0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10, 15, 20,or 25 liters/hour, while operating under pressures up to or greater than5,000 psi, 10,000 psi, 15,000 psi, 20,000 psi, 25,000 psi, 30,000 psi,40,000 psi, or 50,000 psi.

In the illustrated embodiment, the pressure equalizing mechanism 600(e.g., piston-cylinder assembly 601) is radially offset away from thefluid chamber 652, but connects both to the fluid chamber 652 and thefluid flow path through the flow meter 120. For example, the illustratedpressure equalizing mechanism 600 includes first and second conduits orpassages 678 and 680, which couple to the first and second fluidchambers 626 and 628 of the cylinder 604. Thus, the passage 678communicates fluid between the fluid chambers 626 and 652, such that thechambers 626 and 652 are at substantially the same pressure as oneanother. Likewise, the passage 680 communicates fluid between the fluidchamber 628 and the passage 656, such that the chamber 628 and passage656 are at substantially the same pressure as one another. Asappreciated, the piston 602 includes the seals 606 and 608 to isolatethe fluid in the passage 656 from the fluid in the chamber 652.Accordingly, the fluids may be the same or different from one another.The piston 602 also moves along the axis 620 of the cylinder 604 topressure balance the fluid in the passage 656 with the fluid in thechamber 652.

Thus, during an increase in pressure in the passage 656, the fluidpasses through the passage 680 and into the fluid chamber 628, therebybiasing the piston 602 to move from the chamber 628 toward the chamber626 until a pressure balance is reached between the chambers 626 and 628(and thus between the passage 656 and chamber 652). Likewise, during adecrease in pressure in the passage 656, the fluid passes through thepassage 678 and into the fluid chamber 626, thereby biasing the piston602 to move from the chamber 626 toward the chamber 628 until a pressurebalance is reached between the chambers 626 and 628 (and thus betweenthe passage 656 and chamber 652).

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

The invention claimed is:
 1. A system, comprising: a meter, comprising:a conduit having a wall disposed about a fluid flow path; a chamberdisposed outside of the wall of the conduit at least partially along theconduit; a damping material disposed in the chamber outside of the wallof the conduit; and first and second meter elements, wherein the dampingmaterial is disposed between the first and second meter elements.
 2. Thesystem of claim 1, wherein the damping material comprises a plurality ofseparate particles disposed in the chamber outside of the wall of theconduit.
 3. The system of claim 1, wherein the damping materialcomprises a fluid disposed in the chamber outside of the wall of theconduit.
 4. The system of claim 1, wherein the damping materialcomprises one or more structures disposed in the chamber outside of thewall of the conduit.
 5. The system of claim 4, wherein the one or morestructures comprise one or more rings disposed about the wall of theconduit.
 6. The system of claim 1, wherein the damping materialcomprises an elastomer, a polymer, a foam, or a combination thereof,disposed in the chamber outside of the wall of the conduit.
 7. Thesystem of claim 1, wherein the damping material is configured to reduceinterference between the first and second meter elements.
 8. The systemof claim 1, wherein the first meter element comprises a first acousticmeter element, and the second meter element comprises a second acousticmeter element.
 9. The system of claim 1, wherein the first meter elementcomprises a first ultrasonic meter element, and the second meter elementcomprises a second ultrasonic meter element.
 10. The system of claim 1,wherein the meter comprises a flow meter.
 11. The system of claim 1,comprising an underwater component having the meter.
 12. The system ofclaim 1, comprising a chemical injection apparatus having the meter. 13.The system of claim 1, comprising a pressure balancer disposed betweenthe fluid flow path and the chamber.
 14. The system of claim 1,comprising a bellows coupled to the conduit between the fluid flow pathand the chamber.
 15. The system of claim 1, comprising a fluid passagefluidly coupled to the fluid flow path and the chamber.
 16. The systemof claim 15, comprising a piston disposed along the fluid passage.
 17. Asystem, comprising: a conduit; a fluid flow path extending through theconduit; a chamber external to the conduit; and a pressure balancerdisposed between the fluid flow path and the chamber.
 18. The system ofclaim 17, wherein the pressure balancer comprises a bellows coupled tothe conduit between the fluid flow path and the chamber.
 19. The systemof claim 17, wherein the pressure balancer comprises a fluid passagefluidly coupled to the fluid flow path and the chamber.
 20. The systemof claim 19, comprising a piston disposed along the fluid passage. 21.The system of claim 19, wherein the fluid passage comprises an annularfluid passage disposed about the conduit, and the annular fluid passageis fluidly coupled to the fluid flow path via an annular opening coaxialwith the conduit.
 22. The system of claim 17, comprising one or moremeter elements disposed in the chamber.
 23. The system of claim 22,comprising an ultrasonic meter having the one or more meter elements.24. A system, comprising: a conduit; a fluid flow path extending throughthe conduit; a chamber external to and along the conduit; a dampingmaterial disposed in the chamber; and a pressure balancer disposedbetween the fluid flow path and the chamber.
 25. The system of claim 24,comprising one or more meter elements disposed in the chamber.
 26. Thesystem of claim 25, comprising an ultrasonic meter having the one ormore meter elements.
 27. A system, comprising: a meter, comprising: aconduit; a fluid flow path extending through the conduit; a chamberexternal to and along the conduit; a damping material disposed in thechamber; and first and second meter elements, wherein the dampingmaterial is disposed between the first and second meter elements; and anunderwater component having the meter.
 28. The system of claim 2,wherein the plurality of separate particles comprises at least 10separate particles.
 29. The system of claim 2, wherein the plurality ofseparate particles comprises at least 100 separate particles.
 30. Thesystem of claim 2, wherein the plurality of separate particles comprisesrigid particles.
 31. The system of claim 2, wherein the plurality ofseparate particles comprises sand or beads.
 32. The system of claim 2,wherein each separate particle of the plurality of separate particles ismade of an acoustic damping material.
 33. The system of claim 3, whereinthe fluid comprises a protective fluid configured to resist corrosion.34. The system of claim 3, wherein the fluid is isolated from the fluidflow path through the conduit.
 35. The system of claim 1, wherein thedamping material is isolated from the fluid flow path through theconduit.
 36. The system of claim 1, wherein the damping material onlypartially fills the chamber.
 37. The system of claim 1, wherein thechamber is disposed between the wall of the conduit and a surroundinghousing.